Analysis of the reliability of LoRa

TL;DR

This paper models the performance of a single gateway LoRa system considering interference and imperfect orthogonality, revealing significant performance degradation beyond a few kilometers and exponential coverage decline with more devices.

Contribution

It introduces a low-complexity approximate model for LoRa coverage considering interference and orthogonality effects, validated by simulations.

Findings

LoRa coverage is limited to a few kilometers under interference.

Imperfect orthogonality significantly degrades performance beyond a couple of kilometers.

Coverage probability declines exponentially with increasing end devices.

Abstract

This letter studies the performance of a single gateway LoRa system in the presence of different interference considering the imperfect orthogonality effect. It utilizes concepts of stochastic geometry to present a low-complexity approximate closed-form model for computing the success and coverage probabilities under these challenging conditions. Monte Carlo simulation results have shown that LoRa is not as theoretically described as a technology that can cover few to ten kilometers. It was found that in the presence of the combination of signal-to-noise ratio (SNR) and imperfect orthogonality between spreading factors (SF), the performance degrades dramatically beyond a couple of kilometers. However, better performance is observed when perfect orthogonality is considered and SNR is not included. Furthermore, the performance is annulus dependent and slightly improves at the border of the deployment cell annuli. Finally, the coverage probability declines exponentially as the average number of end devices grows.